diff options
author | Giulio Benetti <giulio.benetti@micronovasrl.com> | 2018-07-18 17:23:57 +0300 |
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committer | Maxime Ripard <maxime.ripard@bootlin.com> | 2018-07-19 18:01:52 +0300 |
commit | 490cda5a3c82c4a6a0bbdffe783eb48aec25511a (patch) | |
tree | fc9c2a922b8ce34d62d1eadb6f925f49efbfbd67 /drivers/gpu/drm/sun4i/sun4i_tcon.c | |
parent | 979c11ef39cee79d6f556091a357890962be2580 (diff) | |
download | linux-490cda5a3c82c4a6a0bbdffe783eb48aec25511a.tar.xz |
drm/sun4i: Handle DRM_BUS_FLAG_PIXDATA_*EDGE checking if panel is used.
Handle both positive and negative dclk polarity,
according to bus_flags, taking care of this:
On A20 and similar SoCs, the only way to achieve Positive Edge
(Rising Edge), is setting dclk clock phase to 2/3(240°).
By default TCON works in Negative Edge(Falling Edge), this is why phase
is set to 0 in that case.
Unfortunately there's no way to logically invert dclk through IO_POL
register.
The only acceptable way to work, triple checked with scope,
is using clock phase set to 0° for Negative Edge and set to 240° for
Positive Edge.
On A33 and similar SoCs there would be a 90° phase option, but it divides
also dclk by 2.
This patch is a way to avoid quirks all around TCON and DOTCLOCK drivers
for using A33 90° phase divided by 2 and consequently increase code
complexity.
Check if panel is used. TCON can also handle VGA DAC, then panel could
be empty.
Signed-off-by: Giulio Benetti <giulio.benetti@micronovasrl.com>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180718142357.120998-1-giulio.benetti@micronovasrl.com
Diffstat (limited to 'drivers/gpu/drm/sun4i/sun4i_tcon.c')
-rw-r--r-- | drivers/gpu/drm/sun4i/sun4i_tcon.c | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c b/drivers/gpu/drm/sun4i/sun4i_tcon.c index 3fb084f802e2..9bfb5b967d38 100644 --- a/drivers/gpu/drm/sun4i/sun4i_tcon.c +++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c @@ -17,6 +17,7 @@ #include <drm/drm_encoder.h> #include <drm/drm_modes.h> #include <drm/drm_of.h> +#include <drm/drm_panel.h> #include <uapi/drm/drm_mode.h> @@ -474,6 +475,33 @@ static void sun4i_tcon0_mode_set_rgb(struct sun4i_tcon *tcon, if (mode->flags & DRM_MODE_FLAG_PVSYNC) val |= SUN4I_TCON0_IO_POL_VSYNC_POSITIVE; + /* + * On A20 and similar SoCs, the only way to achieve Positive Edge + * (Rising Edge), is setting dclk clock phase to 2/3(240°). + * By default TCON works in Negative Edge(Falling Edge), + * this is why phase is set to 0 in that case. + * Unfortunately there's no way to logically invert dclk through + * IO_POL register. + * The only acceptable way to work, triple checked with scope, + * is using clock phase set to 0° for Negative Edge and set to 240° + * for Positive Edge. + * On A33 and similar SoCs there would be a 90° phase option, + * but it divides also dclk by 2. + * Following code is a way to avoid quirks all around TCON + * and DOTCLOCK drivers. + */ + if (!IS_ERR(tcon->panel)) { + struct drm_panel *panel = tcon->panel; + struct drm_connector *connector = panel->connector; + struct drm_display_info display_info = connector->display_info; + + if (display_info.bus_flags & DRM_BUS_FLAG_PIXDATA_POSEDGE) + clk_set_phase(tcon->dclk, 240); + + if (display_info.bus_flags & DRM_BUS_FLAG_PIXDATA_NEGEDGE) + clk_set_phase(tcon->dclk, 0); + } + regmap_update_bits(tcon->regs, SUN4I_TCON0_IO_POL_REG, SUN4I_TCON0_IO_POL_HSYNC_POSITIVE | SUN4I_TCON0_IO_POL_VSYNC_POSITIVE, val); |